| BDA Europe Ltd | Manufacturing | 2023 |
| BDA Radiology Ltd | Health & social care | 2019 |
| BDB Management Limited | Administrative & support | 2025 |
| BDD Management Limited | Professional & scientific | 2026 |
| BDJ Transport Ltd | Water & waste | 2024 |
| BE Barbican Limited | Administrative & support | 2023 |
| BE Flex Staff Limited | Administrative & support | 2022 |
| BE Offices Virtual Limited | Administrative & support | 2012 |
| BE Operatives Cleaning Limited | Administrative & support | 2022 |
| BE Operatives Limited | Administrative & support | 2022 |
| BE Technical Services Ltd | Construction | 2025 |
| Be.Electrical Contractors Ltd | Construction | 2014 |
| Beadle Propco Limited | Real estate | 2024 |
| Beaneside Management Company Limited | Households | 1988 |
| Bear Coms Ltd | Information & communication | 2020 |
| Bear Dwellings Limited | Real estate | 2025 |
| Beauchamp Aesthetics Ltd | Health & social care | 2018 |
| Beaver Group Ltd | Financial services | 2023 |
| BEE Commerce London Ltd | Wholesale & retail | 2020 |
| BEE Have Community Community Interest Company | Agriculture & fishing | 2024 |
| Beechfield Court (Watford) Management Company Limited | Households | 1999 |
| Beesons Yard 2024 Ltd | Real estate | 2024 |
| Beetlestone's Garden Maintenance Ltd | Administrative & support | 2015 |
| Bell Heating Limited | Construction | 2022 |
| Bell Walk and Kings Mews Management Limited | Households | 2008 |
| Bellagio Limited | Real estate | 2021 |
| Belliver Limited | Administrative & support | 2002 |
| Belmont Plumbing and Heating Limited | Construction | 2015 |
| Belvedere Capital Limited | Professional & scientific | 2010 |
| Belverdere Solutions Ltd | Wholesale & retail | 2019 |
| BEN Adams Architects Limited | Professional & scientific | 2010 |
| BEN and Bella Ltd | Professional & scientific | 2011 |
| BEN Bridger Interpreting Ltd | Professional & scientific | 2025 |
| Bene and Friends Limited | Hospitality | 2025 |
| Bengeo House Management Co. Limited | Households | 1985 |
| Bengeo Property Investment Ltd | Real estate | 2019 |
| Benjie's Trading Ltd | Construction | 2017 |
| Benn Tyres Limited | Wholesale & retail | 2015 |
| Berale Property Limited | Real estate | 2023 |
| Berbo Buckles Limited | Professional & scientific | 1978 |
| Berbo Limited | Real estate | 2001 |
| Berden Management Co. Limited | Households | 1989 |
| Berkshire Outdoor Education Trust Limited | Education | 1981 |
| Bernard Esher Limited | Wholesale & retail | 1981 |
| Berridge Venues Limited | Hospitality | 2021 |
| Berrybarn Property Ltd | Real estate | 2026 |
| Berryfields (Tiptree) Management Company Limited | Households | 2016 |
| Bert Hardy Limited | Real estate | 1959 |
| Bespoke Air Limited | Construction | 2014 |
| Bespoke Air Supplies Limited | Wholesale & retail | 2025 |
| Bespoke Managed Space Belfast Limited | Administrative & support | 2018 |
| Bespoke Managed Space Euston Limited | Administrative & support | 2016 |
| Best Artificial Grass Ltd | Administrative & support | 2017 |
| Best London Chauffeurs Ltd | Transport & logistics | 2022 |
| BEST4DOGS Limited | Other services | 2025 |
| Betocare UK Limited | Administrative & support | 2012 |
| Better Utility Services Ltd | Construction | 2026 |
| Bevco Limited | Wholesale & retail | 2015 |
| Beverley Homes Investments Ltd | Real estate | 2008 |
| Beverley Homes Limited | Construction | 1992 |
| Beyond the MAT Ltd | Arts & recreation | 2024 |
| BF Events Ltd | Arts & recreation | 2014 |
| BF Weekender Ltd | Arts & recreation | 2024 |
| BGC Roofing Services Limited | Construction | 2017 |
| BH Hub Limited | Other services | 2025 |
| Bierman & Garber Ltd | Hospitality | 2025 |
| Bigbee Limited | Wholesale & retail | 2006 |
| Bigblackhen.Com Ltd | Real estate | 2013 |
| Biggs Grove Construction Limited | Construction | 2019 |
| Billingscroft Invest Ltd | Real estate | 2019 |
| Bionic Bull Holdings Limited | Financial services | 2020 |
| Bionic Bull Limited | Wholesale & retail | 2020 |
| Bionic Bull Properties Limited | Real estate | 2022 |
| Biopharma Laboratories (UK) Limited | Manufacturing | 2007 |
| Birbeck House Flat Management Company Limited | Households | 1989 |
| Birch Farm (Broxbourne) Management Company Limited | Real estate | 2015 |
| Bircherley Rentals Limited | Administrative & support | 2014 |
| Bird in a Biplane Limited | Other services | 2011 |
| Birmon (Broxbourne) Management Company Limited | Households | 1983 |
| Bishop & Knight Estates Limited | Real estate | 2009 |
| Bishops Stortford Visionplus Limited | Wholesale & retail | 1995 |
| Bitstream Productions Limited | Information & communication | 2023 |
| BJG Estates Limited | Real estate | 2019 |
| BJH & JM Hibberd Ltd | Professional & scientific | 2021 |
| BJT Electrical Services Limited | Energy | 2015 |
| BJT Plant Ltd | Construction | 2022 |
| Black Swan Mews Management Company Limited | Households | 1984 |
| Blackdog Games Ltd | Manufacturing | 2011 |
| Blackstar Solutions Limited | Information & communication | 2010 |
| Blackthorne Investments Limited | Administrative & support | 2011 |
| Blaze Pizzeria Ltd | Hospitality | 2025 |
| BLG GAS Limited | Construction | 2004 |
| BLK Sales Ltd | Administrative & support | 2026 |
| BLO by BLO Limited | Other services | 2024 |
| Block Management Online Limited | Households | 2006 |
| Block Scaffold Solutions Ltd | Construction | 2020 |
| Blockbuster Drainage Limited | Administrative & support | 2023 |
| Bloom With Katerina Ltd | Manufacturing | 2026 |
| BLS Limited | Administrative & support | 1997 |
| BLU Marlin Ltd | Administrative & support | 2019 |